Ratchet drive for on body delivery system

ABSTRACT

Ratchet-based drive systems for more reliable and safer drug delivery are provided. The ratchet-based drive systems restrict angular movement and/or linear movement of components that cause a plunger to expel a liquid drug from a drug container. Movement of the components can be restricted to correspond to a predetermined or desired portion of the liquid drug. In the case that control of the drive system is lost or fails, the maximum amount of drug that could be delivered is limited to a known amount, thereby reducing the likelihood of an overdose.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/809,491, filed Nov. 10, 2017, which claims the benefit of U.S.Provisional Application No. 62/420,382, filed Nov. 10, 2016, and U.S.Provisional Application No. 62/439,822, filed Dec. 28, 2016, each ofwhich is incorporated herein by reference in its entirety.

TECHNICAL FIELD

Embodiments generally relate to medication delivery. More particularly,embodiments relate to drive systems for drug delivery devices.

BACKGROUND

An on-body delivery system (OBDS) can be used to deliver drug dosages toa user over time. During a control system failure of the OBDS, there canbe a risk of delivering too much of a drug to the user resulting in apossible drug overdose condition. Accordingly, there is a need for anOBDS having a drive system for delivering a drug to a user that canprevent delivery of too much of a drug to the user during a systemfailure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a first exemplary ratchet drive system.

FIG. 2 illustrates the first ratchet drive system in an idle state.

FIG. 3 illustrates the first ratchet drive system during delivery of adrug.

FIG. 4 illustrates the first ratchet drive system after delivery of thedrug.

FIG. 5 illustrates the first ratchet drive system during a first phaseof reset.

FIG. 6 illustrates the first ratchet drive system during a second phaseof reset.

FIG. 7 illustrates the first ratchet drive system in relation to acontroller.

FIG. 8 illustrates a second exemplary ratchet drive system.

FIG. 9 illustrates the second ratchet drive system after delivery of adrug.

FIG. 10 illustrates the first ratchet drive system in relation to a drugcontainer.

FIG. 11 illustrates a third exemplary ratchet drive system.

FIG. 12 illustrates the third ratchet drive system in an idle state.

FIG. 13 illustrates the third ratchet drive system during delivery of adrug.

FIG. 14 illustrates the third ratchet drive system after delivery of thedrug during a first phase of reset.

FIG. 15 illustrates the third ratchet drive system during a second phaseof reset.

FIG. 16 illustrates a fourth ratchet drive system during delivery of adrug.

FIG. 17 illustrates the fourth ratchet drive system after delivery ofthe drug during a first phase of reset.

FIG. 18 illustrates the fourth ratchet drive system during a secondphase of reset.

FIG. 19 illustrates the first ratchet drive system in relation to apower source.

DETAILED DESCRIPTION

This disclosure presents various systems, components, and methodsrelated to a drug delivery device. Each of the systems, components, andmethods disclosed herein provides one or more advantages overconventional systems, components, and methods.

Various embodiments provide for drug delivery using ratchet-based drivesystems. The ratchet-based drive systems restrict angular movementand/or linear movement of components that cause a plunger to expel aliquid drug from a drug container. Movement of the components can berestricted to expel only a predetermined or desired amount of the liquiddrug. In the case that control of the drive system is lost or fails, themaximum amount of drug that could be delivered is limited to a knownamount, thereby reducing the likelihood of an overdose. Thepredetermined amount of the liquid drug expelled can correspond to anyportion of the liquid drug including a single dose of the liquid drug ora portion thereof.

FIG. 1 illustrates a first exemplary ratchet drive system 100. Theratchet drive system 100 can be incorporated as part of an on-bodydelivery system (OBDS) as described herein. The ratchet drive system 100can include a lead screw 102, a ratchet gear 104, a ratchet carrier 106,a first pawl 108-1, a second pawl 108-2, a first carrier stop 110-1, anda second carrier stop 110-2. As shown in FIG. 1, the lead screw 102 canbe coupled to the ratchet gear 104 and can be positioned through theratchet gear 104 (e.g., through a center hole of the ratchet gear 104).The lead screw 102 can include threads that engage the ratchet gear 104.The lead screw 102 can also be positioned through the ratchet carrier(e.g., through a center hole of the ratchet carrier 106). An end of thelead screw 102 that extends beyond the ratchet carrier 106 can becoupled to a plunger positioned within a drug cartridge (not shown inFIG. 1). The ratchet drive system 100 can be operated such that rotationof the lead screw 102 can cause the plunger to be advanced, therebyexpelling a portion of a liquid drug stored in the drug cartridge. Theratchet drive system 100 can prevent over-delivery (e.g., overdose) ofthe liquid drug (e.g., during system failure of the OBDS incorporatingthe ratchet drive system 100) to ensure safe delivery of the liquid drugand operation of the OBDS as described herein.

The first and second pawls 108-1 and 108-2 can be coupled to the ratchetcarrier 106. As shown in FIG. 1, the first and second pawls 108-1 and108-2 can be positioned to engage the ratchet gear 104 (e.g., the outerteeth of the ratchet gear 104). To expel a portion of the liquid drugfrom the drug container, the ratchet carrier 104 can be rotated (e.g.,about a central axis of rotation 114 in a clockwise direction withrespect to the depiction of the ratchet drive system 100 in FIG. 1). Theratchet carrier 106 can be rotated by an amount corresponding to theposition of the second carrier stop 110-2. That is, the ratchet carrier106 can be rotated such that an extension or protrusion 112 of theratchet carrier 106 moves from the first carrier stop 110-1 to thesecond carrier stop 110-2. The extension 112 of the ratchet carrier 106can be stopped by or can be positioned adjacent to the second carrierstop 110-2 when a desired portion (e.g., a dose or portion thereof) ofthe liquid drug has been expelled from the drug container. The first andsecond carrier stops 110-1 and 110-2 can be coupled to a portion of theOBDS incorporating the ratchet drive system 100.

When the ratchet carrier 106 is rotated from the first carrier stop110-1 toward the second carrier stop 110-2, the ratchet gear 104 can becaused to similarly rotate based on the engagement of the first andsecond pawls 108-1 and 108-2. That is, the first and second pawls 108-1and 108-2 can couple the ratchet carrier 106 to the ratchet gear 104.The rotation of the ratchet gear 104 can cause the lead screw 102 toalso rotate. The ratchet gear 104 can be tightly coupled to the leadscrew 102 to ensure that rotation of the ratchet gear 104 results inrotation of the lead screw 102. Rotation of the lead screw 102 can causethe lead screw 102 to advance in a direction 116 that can be parallel tothe central axis 114. This movement of the lead screw 102 can cause theplunger to move further into the drug container, which can cause aportion of the liquid drug stored therein to be expelled. The lineardisplacement of the lead screw 102 in the direction 116 caused byrotation of the ratchet carrier 106 and the ratchet gear 104 can bebased on a thread pitch of the lead screw 102 which can be adjusted forparticular applications and drug dosages. The amount of liquid drugexpelled can correspond to a predetermined or desired amount of theliquid drug stored in the drug container. In various embodiments, anyportion of the liquid drug can be expelled including, for example, asingle dose of the liquid drug or a portion thereof. Accordingly, invarious embodiments, movement of the ratchet carrier 106 from the firstcarrier stop 110-1 to the second carrier stop 110-2 can cause a singledose of the liquid drug to be expelled from the drug container fordelivery to a patient or user.

After the ratchet carrier 106 has been moved to a position correspondingto the second carrier stop 110-2, the ratchet carrier 106 can be rotatedback to a position corresponding to the first carrier stop 110-2 (e.g.,as shown in FIG. 1). As shown in FIG. 1, the ratchet drive system 100can be in an initial or reset state awaiting activation so as to rotatethe ratchet carrier 106 toward the second carrier stop 110-2 fordelivery of a portion of the liquid drug. Prior to rotating the ratchetcarrier 106 back to a position corresponding the first carrier stop110-1 as shown in FIG. 1, the first and second pawls 108-1 and 108-2 canbe disengaged from the ratchet gear 104. Releasing the first and secondpawls 108-1 and 108-2 from the ratchet gear 104 can prevent the ratchetgear 104 from rotating when the ratchet carrier 106 is rotated backtoward the first carrier stop 110-1. As a result, the position of thelead screw 102 is maintained (e.g., the lead screw 102 is not advancedin the direction 116 when the ratchet carrier 106 is rotated back towardthe first carrier stop 110-1). The first and second pawls 108-1 and108-2 can then re-engage the ratchet gear 104 after the ratchet carrier104 is moved back to the position shown in FIG. 1. The ratchet drivesystem 100 can then await a subsequent activation (e.g., an instructionto rotate the ratchet carrier 106 toward the second carrier stop 110-2)for a next cycle of drug delivery. The first and second pawls 108-1 and108-2 can be coupled to a control system that can rotate or otherwiseadjust the position of the first and second pawls 108-1 and 108-2 toengage and disengage the ratchet gear 104 as desired.

In various embodiments, the ratchet carrier 106 can be positioned aroundthe ratchet gear 104. The ratchet gear 104 can be positioned within anopening of the ratchet carrier 106. In various embodiments, the ratchetdrive system 100 can include a single pawl or more than two pawls.

The operation of the ratchet drive system 100 can prevent over-deliveryof the liquid drug that the ratchet drive system 100 can be used toexpel from the drug container. The second carrier stop 110-2 can preventthe lead screw 102 from rotating more than a desired amount, byrestricting further rotation of the ratchet carrier 106, therebyrestricting further advancement of the plunger coupled to the lead screw102. As a result, further delivery of the liquid drug is prevented.During system failure of the OBDS that incorporates the ratchet drivesystem 100 (e.g., a power failure), the risk of over-delivery of theliquid drug is mitigated by the restricted movement of the lead screw102. Precise dosing of the liquid drug can also be provided by theratchet drive system 100.

The first and second carrier stops 110-1 and 110-2 can be displaced byany amount. As shown in FIG. 1, the first and second carrier stops 110-1and 110-2 are displaced by approximately 180 degrees but are not solimited. The displacement of the first and second carrier stops 110-1and 110-2 can correspond to delivery of a predetermined or desiredamount of the liquid drug when the ratchet carrier 106 is rotated fromthe first carrier stop 110-1 to the second carrier stop 110-2 but is notso limited. In various embodiments, the predetermined amount of theliquid drug can correspond to a single dose of the liquid drug or aportion thereof.

The ratchet carrier 106 can be coupled to a power source to effectuaterotation of the ratchet carrier 106. The power source can comprise amotor but is not so limited. The power source can comprise a mechanicalsystem or an electromechanical system. The power source can cause theratchet carrier 106 to be rotated toward the second carrier stop 110-1based upon an activation signal provided by the OBDS (e.g., acontroller). The activation can be automatically provided or can begenerated responsive to a user input. The power source can cause theratchet carrier 106 to rotate back toward the first carrier stop 110-1immediately after providing the dosage of the liquid drug or after apredetermined delay.

The OBDS in which the ratchet drive system 100 can be incorporated canbe any type of wearable drug delivery system such as, for example, theOmniPod® (Insulet Corporation, Billerica, Mass.) insulin delivery deviceand/or a drug delivery device such as those described in U.S. Pat. Nos.7,303,549, 7,137,964, or U.S. Pat. No. 6,740,059, each of which isincorporated herein by reference in its entirety.

FIG. 2 illustrates a second view of the ratchet drive system 100depicted in FIG. 1. FIG. 1 can represent an isometric view of theratchet drive system 100. FIG. 2 can represent a corresponding frontview of the ratchet drive system 100. As shown in FIG. 2, the extension112 can be positioned adjacent to the first carrier stop 110-1 and thefirst and second pawls 108-1 and 108-2 can be engaged with the ratchetgear 104. FIG. 2 can represent the ratchet drive system 100 in aninitial or idle state prior to being activated to rotate the ratchetcarrier 106. Further, the ratchet carrier 106 can be considered to be inan initial position as depicted in FIG. 2.

FIG. 3 illustrates a front view of the ratchet drive system 100 duringdelivery of the liquid drug. As shown in FIG. 3, the ratchet carrier 106is rotated in a direction 302 (e.g., a clockwise direction relative tothe depiction of the ratchet drive system 100 in FIG. 3). As shown, theextension 112 is moving toward the second carrier stop 110-2. The firstand second pawls 108-1 and 108-2, the ratchet gear 104, and the leadscrew 102 each correspondingly rotate in the direction 302. Further, thelead screw 102 is linearly displaced in a direction parallel to thecentral axis 114.

FIG. 4 illustrates a front view of the ratchet drive system 100 afterdelivery of the liquid drug. As shown in FIG. 4, the ratchet carrier 106has been rotated such that the extension 112 is positioned adjacent tothe second carrier stop 110-2. The second carrier stop 110-2 can preventthe ratchet carrier 106 from rotating any further, thereby preventingfurther linear displacement of the lead screw 102. The rotation of theratchet carrier 106 from the first carrier stop 110-1 to the secondcarrier stop 110-2 can correspond to expelling and delivering a desiredamount or portion of the liquid drug. The ratchet carrier 106 can beconsidered to be in a final position as depicted in FIG. 4.

FIG. 5 illustrates a front view of the ratchet drive system 100 duringan initial resetting of the ratchet drive system 100. As shown in FIG.5, the first and second pawls 108-1 and 108-2 are disengaged from theratchet gear 104. Accordingly, when the ratchet carrier 106 is rotatedback toward the first carrier stop 110-1, the ratchet gear 104 and thelead screw 102 will remain stationary. As a result, none of the liquiddrug will be expelled from the drug container when the ratchet carrier106 is rotated back towards the first carrier stop 110-1.

FIG. 6 illustrates a front view of the ratchet drive system 100 duringfurther resetting of the ratchet drive system 100. As shown in FIG. 6,the ratchet carrier 106 is rotated in a direction 602 (e.g., acounter-clockwise direction relative to the depiction of the ratchetdrive system 100 in FIG. 6). As shown, the extension 112 is moved towardthe first carrier stop 110-1 and is shown positioned adjacent to thefirst carrier stop 110-1 (e.g., corresponding to the initial position ofthe ratchet carrier 106). The first and second pawls 108-1 and 108-2 aresimilarly rotated in the direction 602. After the ratchet carrier 106 isfully rotated back to the initial position (e.g., to a reset or theinitial position), the first and second pawls 108-1 and 108-2 canre-engage the ratchet gear 104 (e.g., as depicted in FIG. 2). Theratchet drive system 100 can then remain in the reset or idle stateuntil being activated again to repeat delivery and the reset cycle asdescribed herein. As with the second carrier stop 110-2, the firstcarrier stop 110-1 can also restrict further rotation of the ratchetcarrier 106.

FIG. 7 illustrates the ratchet drive system 100 with an exemplarycontroller 702. The controller 702 can be coupled to the first carrierstop 110-1, the second carrier stop 110-1, and any other component ofthe ratchet drive system 100 such as the ratchet carrier 106. Thecontroller 702 can direct operation of the ratchet drive system 100. Thefirst and second carrier stops 110-1 and 110-2 can each include one ormore sensors that can inform the controller 702 as to the position ofthe ratchet carrier 106. For example, the first and second carrier stops110-1 and 110-2 can each include a sensor that can inform the controller702 when the extension 112 is touching or in close proximity to one ofthe first and second carrier stops 110-1 and 110-2. Positionalinformation of the ratchet carrier 106 can also be provided to thecontroller 702 from rotation of the ratchet carrier 106. The controller702 can be coupled to the power source of the ratchet drive system 100to direct the power source to rotate the ratchet carrier 106 in adesired direction based on, for example, positional information of theratchet carrier 106 provided by at least the first and second carrierstops 110-1 and 110-2.

During delivery of a portion of the liquid drug, the sensor in thesecond carrier stop 110-2 can send a signal to the controller 702indicating the position of the extension 112 (e.g., when the extensiontouches or is adjacent to the second carrier stop 110-2). The controller702 can adjust or stop the rotation of the ratchet carrier 106 (e.g., inthe direction 302) based on signals received from the second carrierstop 110-2. Further, signals from the second carrier stop 110-2 canallow the controller 702 to maintain a count of the number of times theextension 112 has reached the second carrier stop 110-2. In this way, acount of the number of times the drug is delivered or expelled can bemaintained, along with a count of the remaining number of times the drugcan be expelled. In various embodiments, when the portion expelledcorresponds to a desired dose of the liquid drug or portion thereof, acount of the number of doses of drug delivered or expelled can bemaintained, along with a count of remaining doses.

The sensor in the first carrier stop 110-1 can similarly send a signalto the controller 702 indicating the position of the extension 112(e.g., when the extension touches or is adjacent to the first carrierstop 110-1). The controller 702 can adjust or stop the rotation of theratchet carrier 106 (e.g., in the direction 602) based on signalsreceived from the first carrier stop 110-1. Signals from the firstcarrier stop 110-1 can also be used to maintain a count of the number oftimes the liquid drug is delivered or expelled and a count of how manymore times the drug can be expelled before the drug container issubstantially empty. As described above, in various embodiments, whenthe portion expelled corresponds to a desired dose of the liquid drug orportion thereof, the signals from the first carrier stop 110-1 canenable a count of the number of doses of drug delivered or expelled canbe maintained, along with a count of remaining doses.

FIG. 8 illustrates a second exemplary ratchet drive system 800. Theratchet drive system 800 can include substantially the same componentsof the ratchet drive system 100 and can operate in a substantiallysimilar manner as the ratchet drive system 100. The ratchet drive system800 can include a single carrier stop 802 (as opposed to two carrierstops as included with the ratchet drive system 100). The ratchet drivesystem 800 as shown in FIG. 8 can be in an initial position or idlestate prior to being activated to deliver a portion of the liquid drug.When activated or instructed to deliver a portion of the liquid drug,the ratchet carrier 106 can rotate in a clockwise direction (relative tothe depiction of the ratchet drive system 800 in FIG. 8). The extension112 can rotate until reaching the other side of the carrier stop 802. Indoing so, the ratchet gear 104 and the lead screw 102 can similarlyrotate. A desired amount of drug can be expelled from the drug containerbased on this rotation of the ratchet carrier 106.

The carrier stop 802 can include one or more sensors for detecting aposition of the ratchet carrier 106. As with the ratchet drive system100, the ratchet drive system 800 can further include a controller fordirecting operation of the ratchet drive system 800 based on signalsreceived from one or more sensors of the carrier stop 802. Like theratchet drive system 100, the ratchet drive system 800 can be coupled toa power source (e.g., a motor) to provide an input for rotating theratchet carrier 106.

FIG. 9 illustrates the ratchet drive system 800 after delivering aportion of the liquid drug. As shown in FIG. 9, the ratchet carrier 106has rotated such that the extension 112 is positioned on the other sideof the carrier stop 802 (as compared to the position of the extension112 as shown in FIG. 8). The first and second pawls 108-1 and 108-2 andthe ratchet gear 104 have similarly rotated. The ratchet carrier 106 hasrotated just under 360 degrees. For a motor power source, theimplementation of the ratchet drive system 800 with the single carrierstop 802 can reduce the number of motor cycles used to deliver the sameadvancement of the lead screw 102.

FIG. 10 illustrates a side view of the ratchet drive system 100 inrelationship to a drug container 1002. For simplicity, the first andsecond carrier stops 110-2 and 110-2 are not shown. As shown in FIG. 10,the lead screw 102 extends through and beyond the ratchet carrier 106(e.g., through a central hole or opening of the ratchet carrier 106).The ratchet carrier 106 can be coupled to or positioned adjacent to thedrug container 1002. The drug container 1002 can include an area orreservoir 1004 for holding a liquid drug as described herein. The drugcontainer 1002 can further include a port 1006 through which the liquiddrug stored in the reservoir 1004 can be expelled out of the drugcontainer 1002.

The lead screw 102 can be coupled to a plunger 1008. The plunger 1008can define a boundary of the reservoir 1004. As described herein, whenthe ratchet carrier 106 is rotated in a first direction to initiate drugdelivery, the lead screw 102 can rotate about the central axis 114. As aresult, the lead screw 102 can move in the direction 116 and can push onthe plunger 1008 to drive the plunger 1008 in the direction 116 as well.The movement of the plunger 1008 in the direction 116 can expel aportion of the liquid drug stored in the reservoir 1004 from the drugcontainer 1002 (e.g., through the exit port 1006 for subsequent deliveryto a patient).

The ratchet drive system 100 and additional components depicted in FIG.10 can be incorporated into an OBDS as described herein. The ratchetdrive system 800 can be similarly coupled to the additional componentsdepicted in FIG. 10 as will be understood by a person of ordinary skillin the art. As described herein, the ratchet drive systems 100 and 800can prevent overdose situations that can occur with conventional drivesystems for drug delivery devices by restricting rotational movement andusing multiple rotational cycles to deliver one or more desired orpredetermined doses of the liquid drug.

For example, if the power source for the ratchet drive system 100suddenly and/or catastrophically failed at any time (e.g., duringdelivery of a dose and/or movement of ratchet carrier 106 toward thesecond carrier stop 110-2), then the second carrier stop 110-2 canrestrict the angular movement of the ratchet carrier 106. As a result,delivery of any further drug can be prevented. In particular, the secondcarrier stop 110-2 can block movement of the ratchet carrier 106 thatcould be caused by any force such as inertia or gravity that may attemptto rotate the ratchet carrier 106 any further. As described herein, themaximum angular movement of the ratchet carrier 106 can be restricted bya desired amount such that the angular displacement corresponds to adesired drug delivery, ensuring that drug delivery can be limited to adesired amount in a runaway operation condition. In various embodiments,as described above in relation to the other disclosed ratchet drivesystems, any portion of the stored liquid drug can be delivered duringeach cycle of movement including, for example, a single desired dose ofthe liquid drug or a portion thereof. The ratchet drive system 800provides the same prevention of overdose during such conditions by thecarrier stop 802 similarly restricting movement of the ratchet carrier106.

FIG. 19 illustrates the ratchet drive system 100 with an exemplary powersource 1906. The power source 1906 can be a motor. The motor 1906 caninterface with the ratchet drive system 100 as shown to facilitatemovement of the ratchet carrier 106 as described herein.

In various embodiments, as shown in FIG. 19, the ratchet carrier 106 caninclude gear teeth 1902. The gear teeth 1902 can be positioned along aperimeter of the ratchet carrier 106 and can project from the ratchetcarrier 106. A gear 1904 can be coupled to the ratchet carrier 106 asshown. In various embodiments, teeth of the gear 1904 can interface withthe gear teeth 1902 of the ratchet carrier 106. The gear 1904 can becoupled to the motor 1906. The motor 1906 can rotate the ratchet gear1906 as desired and as described herein by rotation of the gear 1904 aswill be understood by a person of ordinary skill in the art.Accordingly, the motor 1906 can control delivery of the liquid drug byrotating the ratchet carrier 106 as desired and can rotate the ratchetcarrier 106 back to an idle state after delivery. The motor 1906 caninitiate rotation automatically or based on user input.

In various embodiments, the ratchet drive systems 100 and 800 can beconfigured to enable a portion of the drug to be delivered based on bothforward and backwards rotation of the ratchet carrier 106 as will beappreciated by one skilled in the art.

FIG. 11 illustrates a third exemplary ratchet drive system 1100. As withthe ratchet drive systems 100 and 800, the ratchet drive system 1100 canbe used in an OBDS as described herein. The ratchet drive system 1100can include a rack 1102, a plunger 1104, a power source 1106, an arm1108, a pawl 1110, and a drug container 1112. As shown in FIG. 11, therack 1102 can be coupled to the plunger 1104. The plunger 1104 can bepositioned within the drug container 1112. The power source 1106 can be,for example, a motor or a linear actuator. The power source 1106 can becoupled to the arm 1108. The pawl 1110 can be coupled to the arm 1108.

The ratchet drive system 1100 can be operated such that linear movementof the arm 1108 (e.g., in a direction away from the power source 1106)can drive the plunger 1104 further into the drug container 1112, therebyexpelling a portion of a liquid drug stored in the drug cartridge. Likethe ratchet drive systems 100 and 800, the ratchet drive system 1100 canprevent over-delivery (e.g., overdose) of the liquid drug (e.g., duringsystem failure of the OBDS incorporating the ratchet drive system 1100)to ensure safe delivery of the liquid drug and operation of the OBDS asdescribed herein.

FIG. 11 can represent the ratchet drive system 1100 in an idle stateprior to activation. When activated, the ratchet drive system 1100 canoperate to deliver a desired amount of the stored liquid drug to a user.Specifically, when activated, the power source 1106 can cause the arm1108 to extend (e.g., in a direction away from the power source 1106).When the arm 1108 extends, the rack 1102 can be caused to move forward(e.g., in the same direction that the arm 108 extends) by the couplingof the arm 1108 to the rack 1102 by the pawl 1110. As a result, theplunger 1104 is driven further into the drug container, expelling aportion of the stored liquid drug.

The arm 1108 can be sized and controlled to extend a desired amount awayfrom the power source 1106 when the ratchet drive system 1100 isactivated. By limiting the amount by which the arm 1108 can extend(e.g., to a maximum extension amount), the movement of the plunger 1104can likewise be limited. In this way, over-delivery can be mitigated bylimiting the amount of liquid drug that can be expelled during eachactivation of the ratchet drive system 1100. After the arm 1108 is fullyextended, the arm 1108 can be operated to move back to its originalposition (e.g., retracted back toward the power source 1106). Theposition of the rack 1102 can be maintained by having the pawl 1110disengage the rack 1102 prior to the arm 1108 moving in a direction backtoward the power source 1108.

The ratchet drive system 1100 can be used with the same OBDSs describedin relation to the ratchet drive systems 100 and 800. Like the ratchetdrive systems 100 and 800, a controller can be used with the ratchetdrive system 1100 to direct operation of the power source 1106 andtherefore delivery of the liquid drug. The controller can directoperation of the power source 1106 based on, for example, positionalinformation of the plunger 1104, the rack 1102, and/or the arm 1108. Thecontroller can track delivery of the liquid drug to determine a numberof times a portion of the drug is delivered and/or an amount of liquiddrug remaining as described herein, for example based on the movement ofthe arm 1108. The drug container 1112, like the drug container 1002, caninclude a port for the liquid drug (not shown in FIG. 11).

FIG. 12 illustrates a second view of the ratchet drive system 1100depicted in FIG. 11. FIG. 11 can represent an isometric view of theratchet drive system 1100. FIG. 12 can represent a corresponding sideview of the ratchet drive system 1100. As shown in FIG. 12, the pawl1110 couples the arm 1108 to the rack 1102. The drug container 1112includes a reservoir 1202 for storing the liquid drug. The reservoir1202 can be defined in part by the plunger 1104 and an end of the drugcontainer (opposite to the plunger 1104; not shown in FIG. 12). The endof the drug container 1112 can include a port or other opening allowingthe liquid drug stored in the reservoir 1202 to be expelled as theplunger 1104 is advanced toward the end of the drug container 1112.

FIG. 13 illustrates the ratchet drive system 1100 during delivery of theliquid drug. As shown in FIG. 13, the arm 1108 extends in a direction1302. As a result, the rack 1102 and plunger 1104 are advanced in adirection 1304 as shown. The advancement of the plunger 1104 furtherinto the drug container 1112 can cause a portion of the liquid drugstored in the reservoir 1202 to be expelled from the drug container1112. The arm 1108 can be sized such that extension of the arm 1108 inthe direction 1302 corresponds to a desired amount of the liquid drugbeing expelled (e.g., a single dose or a portion thereof). As describedherein, the length of the arm 1108 can be limited such that only adesired amount of the liquid drug is expelled by moving the rack 1102and the plunger 1104 by the amount the arm 1108 is extended. Runawayoperation and over-delivery of the liquid drug can therefore be avoidedin case of a system failure (e.g., power loss) of the OBDS in which theratchet drive system 1100 is incorporated since further movement of therack 1102 by the arm 1108 is restricted.

After the arm 1108 is extended by the set amount, the arm 1108 and therack 1102 can come to a rest. The controller can track the movement ofthe arm 1008 and can maintain a count of the number of times the arm1108 is extended to expel the liquid drug. The amount the arm 1108 isextended can correspond to any desired amount of drug to be delivered toa user including, for example, a single dose of the liquid drug, or aportion thereof.

FIG. 14 illustrates the ratchet drive system 1100 initiating a return toits initial or idle state. As shown in FIG. 14, the arm 1108 is a movedin a direction 1402 back toward the power source 1106. The pawl 1110 isshaped so as to rotate in a direction 1404 as the arm 1108 is moved inthe direction 1402. As a result, the pawl 1110 is disengaged from therack 1102. The rack 1102 therefore does not move and remains stationaryas the arm 1108 is moved backwards (e.g., in the direction 1402). Invarious embodiments, the pawl 1110 can be controlled to rotate in thedirection 1404 to facilitate disengagement from the rack 1102. The arm1108 can be retracted back to an original position corresponding to theposition of the arm 1108 prior to activation.

FIG. 15 illustrates the ratchet drive system 1100 re-engaging the rack1102. As shown in FIG. 15, the arm 1108 is in close proximity to thepower source 1106. When the arm 1108 stops moving, the pawl 1110 rotatesin a direction 1502 to re-engage the rack 1102. Once the pawl 1110re-engages the rack 1102, the ratchet drive system 1110 can bere-activated to a deliver a subsequent amount of the liquid drug.

In various embodiments, the stroke of the arm 1108 can be greater than alength of one tooth on of the rack 1102 so as to provide clearance forthe pawl 1110 to rotate as described herein without hitting a tooth ofthe rack 1102. In various embodiments, the rotational movement of thepawl 1110 and/or the linear movement of the pawl 1110 can be passivemovements, as the angle of the rack 1102 can push the pawl 1110 out ofthe way. In such embodiments, the pawl 1110 can be spring loaded, forexample, and biased to be in the engaged position as shown in FIG. 15.As described above, in various other embodiments, the pawl 1110 can beactively rotated as desired for retraction, using a separate powersource for example.

As described herein, the ratchet drive system 1100 can also preventoverdose situations that can occur with conventional drive systems fordrug delivery devices by restricting linear movement and using multipleactuations cycles to deliver one or more doses of the liquid drug. Forexample, if the power source 1108 suddenly and/or catastrophically failsat any time (e.g., during delivery of a dose and/or when the arm 1108 isbeing extended), then the length of the arm 1108 (e.g., maximumextension of the arm 1108) can restrict the amount by which the rack1102 and the plunger 1104 can move. As a result, delivery of any furtherdrug can be prevented.

FIG. 16 illustrates a fourth exemplary ratchet drive system 1600. Theratchet drive system 1600 can be a variation of the ratchet drive system1100. As with the ratchet drive systems 100, 800, and 1100, the ratchetdrive system 1600 can be used in an OBDS as described herein and canprovide the same benefits as the ratchet drive system 1600. The ratchetdrive system 1600 can include the rack 1102, the plunger 1104, the powersource 1106, the arm 1108, a pawl 1606, and the drug container 1112. Theratchet drive system 1600 can operate in a substantially similar manneras the ratchet system 1100 with the exceptions described herein.

As shown in FIG. 16, the pawl 1606 can be coupled to the arm 1108. Asopposed to rotating like the pawl 1110, the pawl 1606 can be coupled tothe arm 1108 and arranged to move up and down (e.g., towards and awayfrom the rack 1102) to engage and disengage from the rack 1102 asdescribed further herein.

FIG. 16 illustrates the ratchet drive system 1600 during delivery of theliquid drug. As shown in FIG. 16, the arm 1108 extends in a direction1602 and the pawl 1606 is engaged with the rack 1102. As a result, therack 1102 and the plunger 1104 are advanced in a direction 1604 asshown. The advancement of the plunger 1104 further into the drugcontainer 1112 can cause a portion of the liquid drug stored in thereservoir 1202 to be expelled from the drug container 1112 as describedabove in relation to the ratchet drive system 1100. Once the arm 1108 isextended by a desired or predetermined amount, the arm 1108 and the rack1102 can come to rest.

FIG. 17 illustrates the ratchet drive system 1600 initiating a return toits initial or idle state. As shown in FIG. 17, the arm 1108 is moved ina direction 1702 back toward the power source 1106. The pawl 1606 canmove downward in a direction 1704 as the arm 1108 is moved in thedirection 1702. As a result, the pawl 1606 is disengaged from the rack1102. The rack 1102 therefore does not move and remains stationary asthe arm 1108 is moved backwards (e.g., in the direction 1702). Invarious embodiments, the movement of the pawl 1606 in the direction 1704can be passive, for example, based on a shape of the pawl 1606 andinteraction with the teeth of the rack 1102. In various embodiments, thepawl 1606 can be spring loaded to enable disengagement and re-engagementof the pawl 1606 with the rack. In various embodiments, the pawl 1606can be controlled, for example by a power source, to move in thedirection 1704.

FIG. 18 illustrates the ratchet drive system 1600 re-engaging the rack1102. As shown in FIG. 18, the arm 1108 is in close proximity to thepower source 1106. When the arm 1108 stops moving, the pawl 1606 canmove upwards in a direction 1802 to re-engage the rack 1102. Once thepawl 1606 re-engages the rack 1102, the ratchet drive system 1600 can bere-activated to a deliver a subsequent predetermined amount of theliquid drug. As described above, the movement of the pawl 1606 (e.g., inthe direction 1802) can be passive movement or can be activelycontrolled.

The following examples pertain to additional embodiments:

Example 1 is a ratchet drive system comprising a ratchet gear, a leadscrew coupled to the ratchet gear, an end of the lead screw coupled to aplunger positioned in a drug container, a ratchet carrier positionedaround the ratchet gear, a first pawl coupled to the ratchet carrier anda second pawl coupled to the ratchet carrier, the first and second pawlsconfigured to selectively engage the ratchet gear, and a first carrierstop configured to restrict rotation of the ratchet carrier in a firstdirection.

Example 2 is an extension of Example 1 or any other example disclosedherein, comprising a second carrier stop configured to restrict rotationof the ratchet carrier in a second, opposite direction.

Example 3 is an extension of Example 2 or any other example disclosedherein, wherein the first and second pawls are configured to engage theratchet gear when the ratchet carrier is rotated in the first direction,thereby coupling the ratchet carrier to the ratchet gear.

Example 4 is an extension of Example 3 or any other example disclosedherein, wherein the ratchet gear and the lead screw are configured torotate in the first direction when the ratchet carrier is rotated in thefirst direction.

Example 5 is an extension of Example 4 or any other example disclosedherein, wherein the lead screw is configured to move in a lineardirection when the ratchet carrier is rotated in the first direction,the linear direction parallel to an axis of rotation of the ratchetcarrier.

Example 6 is an extension of Example 5 or any other example disclosedherein, wherein the lead screw is configured to move the plunger in thelinear direction and further into the drug container when the ratchetcarrier is rotated in the first direction.

Example 7 is an extension of Example 6 or any other example disclosedherein, wherein the plunger is configured to expel a portion of a liquiddrug stored in the drug container when moved in the linear direction.

Example 8 is an extension of Example 7 or any other example disclosedherein, wherein a predetermined dose of the liquid drug is expelled fromthe drug container when the ratchet carrier is rotated in the firstdirection from an initial position corresponding to the second carrierstop to a final position corresponding to the first carrier stop.

Example 9 is an extension of Example 8 or any other example disclosedherein, wherein the first and second carrier stops are displaced byapproximately 180 degrees.

Example 10 is an extension of Example 8 or any other example disclosedherein, wherein the first carrier stop is configured to prevent theratchet carrier from rotating further in the first direction.

Example 11 is an extension of Example 8 or any other example disclosedherein, wherein the first and second pawls are configured to disengagethe ratchet gear when the ratchet carrier is rotated in the seconddirection, thereby decoupling the ratchet gear from the ratchet carrier.

Example 12 is an extension of Example 11 or any other example disclosedherein, wherein the ratchet gear and the lead screw are configured toremain stationary when the ratchet gear is rotated in the seconddirection.

Example 13 is an extension of Example 11 or any other example disclosedherein, wherein the ratchet carrier is rotated in the second directionto return to the initial position to reset the ratchet drive system.

Example 14 is an extension of Example 13 or any other example disclosedherein, wherein the first and second pawls are configured to re-engagethe ratchet gear when the ratchet drive system is reset.

Example 15 is an extension of Example 13 or any other example disclosedherein, further comprising a power source for rotating the ratchetcarrier.

Example 16 is an extension of Example 51 or any other example disclosedherein, wherein the ratchet gear comprises gear teeth position around aperimeter of the ratchet carrier, wherein the ratchet drive systemfurther comprises a gear coupled to the gear teeth of the ratchetcarrier and coupled to the power source, wherein the power sourcerotates the ratchet carrier by rotating the gear.

Example 17 is an extension of Example 16 or any other example disclosedherein, further comprising a controller, the controller configured tocontrol operation of the power source and rotation of the ratchetcarrier.

Example 18 is an extension of Example 17 or any other example disclosedherein, wherein the first and second carrier stops each include a sensorconfigured to detect when the ratchet carrier is in the final positionand the initial position, respectively.

Example 19 is an extension of Example 18 or any other example disclosedherein, wherein each sensor is configured to transmit a signal to thecontroller to indicate at least one of the final position and theinitial position of the ratchet carrier.

Example 20 is an extension of Example 18 or any other example disclosedherein, wherein the controller is configured to maintain a count of anumber of predetermined doses of the liquid drug that have beendelivered based on the signals transmitted by the sensors.

Example 21 is an extension of Example 1 or any other example disclosedherein, wherein the drive system is part of an on-body delivery system(OBDS).

Example 22 is a method comprising rotating a ratchet carrier in a firstdirection from an initial position to a final position, rotating aratchet gear in the first direction based on rotating the ratchetcarrier, rotating a lead screw in the first direction based on rotatingthe ratchet gear, moving the lead screw in a linear direction parallelto an axis of rotation of the lead screw based on rotating the leadscrew, the lead screw coupled to a plunger positioned in a drugcontainer holding a liquid drug, and moving the plunger in the lineardirection further into the drug container based on moving the leadscrew, thereby expelling a dose of the liquid drug from the drugcontainer.

Example 23 is an extension of Example 22 or any other example disclosedherein, further comprising restricting rotation of the ratchet carrierbeyond the final position based on a position of a first carrier stop.

Example 24 is an extension of Example 23 or any other example disclosedherein, further comprising detecting the final position of the ratchetcarrier based on a sensor of the first carrier stop.

Example 25 is an extension of Example 24 or any other example disclosedherein, further comprising maintaining a count of a number of doses ofthe liquid drug expelled based on detecting the final position of theratchet carrier.

Example 26 is an extension of Example 25 or any other example disclosedherein, further comprising rotating the ratchet gear in a seconddirection opposite the first direction from the final position to theinitial position.

Example 27 is an extension of Example 26 or any other example disclosedherein, further comprising decoupling the ratchet carrier from theratchet gear prior to rotating the ratchet gear in the second direction,thereby preventing the ratchet gear and the lead screw from rotating inthe second direction.

Example 28 is an extension of Example 27 or any other example disclosedherein, further comprising restricting rotation of the ratchet carrierbeyond the initial position based on a position of a second carrierstop.

Example 29 is an extension of Example 28 or any other example disclosedherein, further comprising detecting the initial position of the ratchetcarrier based on a sensor of the second carrier stop.

The following examples pertain to further additional embodiments:

Example 1 is a ratchet drive system, comprising a power source, an armcoupled to the power source, a pawl coupled to an end of the arm, a rackcoupled to the arm through the pawl, and a plunger coupled to the end ofthe rack, the plunger positioned within a drug container storing aliquid drug.

Example 2 is an extension of Example 1 or any other example disclosedherein, the power source configured to cause the arm to extend in afirst direction, thereby moving the rack in the first direction.

Example 3 is an extension of Example 2 or any other example disclosedherein, wherein the plunger is configured move in the first directionfurther into the drug container when the rack is moved in the firstdirection.

Example 4 is an extension of Example 3 or any other example disclosedherein, wherein a portion of the liquid drug is expelled from the drugcontainer when the plunger is moved in the first direction.

Example 5 is an extension of Example 4 or any other example disclosedherein, wherein a predetermined dose of the liquid drug is expelled fromthe drug container when the arm is moved in the first direction from aninitial position to a final position.

Example 6 is an extension of Example 5 or any other example disclosedherein, wherein the final position corresponds to a maximum extension ofthe arm.

Example 7 is an extension of Example 6 or any other example disclosedherein, wherein the pawl is configured to disengage the rack after thearm is in the final position.

Example 8 is an extension of Example 7 or any other example disclosedherein, wherein the power source is configured to cause the arm to movein a second, opposite direction after the arm is in the final position.

Example 9 is an extension of Example 8 or any other example disclosedherein, wherein the rack and the plunger are configured to remainstationary when the arm moves in the second direction.

Example 10 is an extension of Example 9 or any other example disclosedherein, wherein the ratchet drive system is reset when the arm moves inthe second direction to return to the initial position.

Example 11 is an extension of Example 10 or any other example disclosedherein, wherein the pawl is configured to re-engage the rack when theratchet drive system is reset.

Example 12 is an extension of Example 11 or any other example disclosedherein, further comprising a controller for activating movement of thearm in the first direction and the second direction based on control ofthe power source.

Example 13 is an extension of Example 12 or any other example disclosedherein, wherein the power source is a motor.

Example 14 is an extension of Example 12 or any other example disclosedherein, wherein the power source is a linear actuator.

Example 15 is an extension of Example 12 or any other example disclosedherein, wherein the controller is configured to maintain a count of anumber of predetermined doses of the liquid drug that have been expelledbased on the movement of the arm.

Example 16 is an extension of Example 1 or any other example disclosedherein, wherein the drive system is part of an on-body delivery system(OBDS).

Example 17 is a method comprising extending an arm in a first directionfrom an initial position to a final position, moving a rack in the firstdirection based on extending the arm, the rack coupled to a plungerpositioned in a drug container holding a liquid drug, and moving theplunger in the first direction further into the drug container based onmoving the rack, thereby expelling a dose of the liquid drug from thedrug container.

Example 18 is an extension of Example 17 or any other example disclosedherein, further comprising detecting the final position of the arm.

Example 19 is an extension of Example 18 or any other example disclosedherein, further comprising maintaining a count of a number of doses ofthe liquid drug expelled based on detecting the final position of thearm.

Example 20 is an extension of Example 19 or any other example disclosedherein, further comprising coupling the arm to the rack with a pawl.

Example 21 is an extension of Example 20 or any other example disclosedherein, further comprising moving the pawl to decouple the arm from therack after the arm is extended to its final position.

Example 22 is an extension of Example 21 or any other example disclosedherein, further comprising rotating the pawl to decouple the arm fromthe rack after the arm is extended to its final position.

Example 23 is an extension of Example 21 or any other example disclosedherein, further comprising moving the pawl in a direction away from therack to decouple the arm from the rack after the arm is extended to itsfinal position.

Example 24 is an extension of Example 21 or any other example disclosedherein, further comprising moving the arm in a second direction oppositethe first direction to retract the arm to the initial position from thefinal position.

Example 25 is an extension of Example 24 or any other example disclosedherein, further comprising restricting movement of the rack and theplunger in the second direction.

Certain embodiments of the present invention were described above. Itis, however, expressly noted that the present invention is not limitedto those embodiments, but rather the intention is that additions andmodifications to what was expressly described herein are also includedwithin the scope of the invention. Moreover, it is to be understood thatthe features of the various embodiments described herein were notmutually exclusive and can exist in various combinations andpermutations, even if such combinations or permutations were not madeexpress herein, without departing from the spirit and scope of theinvention. In fact, variations, modifications, and other implementationsof what was described herein will occur to those of ordinary skill inthe art without departing from the spirit and the scope of theinvention. As such, the invention is not to be defined only by thepreceding illustrative description.

What is claimed is:
 1. An on-body drug delivery system, comprising: areservoir configured to contain a liquid drug; a plunger configured toseal an end of the reservoir; a rack having a plurality of teeth andcoupled to the plunger, wherein the rack is configured to move theplunger within the reservoir; an arm having a pawl configured to engagethe rack; and a power source configured to extend and retract the arm,wherein extending the arm causes the plunger to expel an amount of theliquid drug.
 2. The system of claim 1, wherein the arm is sized suchthat extension of the arm is in a direction parallel to movement of therack corresponds to the amount of the liquid drug being expelled.
 3. Thesystem of claim 1, wherein the arm has a length enabling the amount ofthe liquid drug expelled by the plunger a desired amount of the liquiddrug to be when a corresponding amount of the length of the arm isextended.
 4. The system of claim 1, wherein the power source is operableto move the arm backward in a direction away from the plunger.
 5. Thesystem of claim 4, wherein the pawl is configured to: disengage the rackwhen the arm is moved backward.
 6. The system of claim 1, wherein thepawl is configured to: rotate away from when the rack when the arm ismoved.
 7. The system of claim 1, wherein the plunger is configured toexpel a portion of a liquid drug stored in the reservoir when moved in alinear direction.
 8. The system of claim 1, further comprising: acontroller couple to the power source, wherein the controller isoperable to control the power source.
 9. The system of claim 8, whereinthe controller is further operable to: track movement of the arm; andmaintain a count of a number of times the arm is moved to expel theliquid drug.
 10. A method, comprising: extending an arm coupled to pawlthat is engaged with a rack in a first direction, wherein the arm isdriven from a first pos from an initial position to a final position; inresponse to extending the arm, expelling a dose of a liquid drug from adrug container by a plunger coupled to the rack; retracting the arm in asecond direction, opposite the first direction; in response toretracting the arm in the second direction, disengaging the pawl fromthe rack; and stopping retracting of the arm in the second directionupon return to the initial position in preparation for expelling anotherdose of the liquid drug.
 11. The method of claim 10, further comprising:re-engaging the rack by the pawl when the arm stops retracting in thesecond direction.
 12. The method of claim 11, wherein disengaging thepawl from the rack comprises: rotating an end of the pawl to disengagethe pawl from a tooth on the rack.
 13. The method of claim 10, whereinextending the arm in the first direction further comprises: advancingthe plunger toward an end of the drug container.
 14. The method of claim10, further comprising: activating a power source coupled to the arm todeliver the dose of the liquid drug by causing the power source toextend the arm.
 15. The method of claim 14, further comprising: afterreturning to the initial position, reactivating the power source to adeliver the other dose of the liquid drug by causing the power source toextend the arm.